Fix Memory DOS in Icns, Ico and Blp Image Plugins

Some container plugins that could contain images of other formats,
such as the ICNS format, did not properly check the reported size of
the contained image. These images could cause arbitrariliy large
memory allocations.

This is fixed for all locations where individual *ImageFile classes
are created without going through the usual Image.open method.

Tests/test_file_icns.py

@@ -140,3 +140,9 @@ def test_not_an_icns_file():
     with io.BytesIO(b"invalid\n") as fp:
         with pytest.raises(SyntaxError):
             IcnsImagePlugin.IcnsFile(fp)
+
+
+def test_icns_decompression_bomb():
+    with pytest.raises(Image.DecompressionBombError):
+        im = Image.open('Tests/images/oom-8ed3316a4109213ca96fb8a256a0bfefdece1461.icns')
+        im.load()

src/PIL/BlpImagePlugin.py

@@ -353,6 +353,7 @@ class BLP1Decoder(_BLPBaseDecoder):
         data = jpeg_header + data
         data = BytesIO(data)
         image = JpegImageFile(data)
+        Image._decompression_bomb_check(image.size)
         self.tile = image.tile  # :/
         self.fd = image.fp
         self.mode = image.mode

src/PIL/IcnsImagePlugin.py

@@ -105,6 +105,7 @@ def read_png_or_jpeg2000(fobj, start_length, size):
     if sig[:8] == b"\x89PNG\x0d\x0a\x1a\x0a":
         fobj.seek(start)
         im = PngImagePlugin.PngImageFile(fobj)
+        Image._decompression_bomb_check(im.size)
         return {"RGBA": im}
     elif (
         sig[:4] == b"\xff\x4f\xff\x51"
@@ -121,6 +122,7 @@ def read_png_or_jpeg2000(fobj, start_length, size):
         jp2kstream = fobj.read(length)
         f = io.BytesIO(jp2kstream)
         im = Jpeg2KImagePlugin.Jpeg2KImageFile(f)
+        Image._decompression_bomb_check(im.size)
         if im.mode != "RGBA":
             im = im.convert("RGBA")
         return {"RGBA": im}

src/PIL/IcoImagePlugin.py

@@ -178,6 +178,7 @@ class IcoFile:
         if data[:8] == PngImagePlugin._MAGIC:
             # png frame
             im = PngImagePlugin.PngImageFile(self.buf)
+            Image._decompression_bomb_check(im.size)
         else:
             # XOR + AND mask bmp frame
             im = BmpImagePlugin.DibImageFile(self.buf)